What STP should provide (GTE)

- the range of fuel consumption change is 1:20 for engines without FCC and 1: 100 for engines with FCC;

- maximum fuel pressure in front of the nozzles 9 MPa;

- the minimum fuel pressure at the engine inlet is 0,03. .0,05 MPa;

- serviceability at a fuel temperature from -60 ° C at the engine inlet to +110. + 130 ° С in front of the nozzles;

- the ability to work in the presence of water in the fuel in the amount of 0,005. 0,02% (mass.);

- fuel filtration fineness 16. 25 microns with the possibility of short-term operation when passing contaminated fuel past the filter;

- reliability (mean time between failures in flight 3 107 h);

- resource of aggregates up to 30 thousand hours (for engines of mainline aircraft);

- the ability to diagnose units and the degree of their wear, operation according to their technical condition;

- minimum weight, power consumption of units, cost of production and operation.

The necessary degree of compliance with these requirements depends on the engine, which is installed on the system, such as its drive units and pumps, the possibility of obtaining the required characteristics, including those related to the thermal state of the system and fuel quality, which affect its lubricity. The maximum allowable temperature of the fuel entering the combustor nozzles is determined by the level at which fuel maintains its physical and chemical properties.

The fuel systems of aircraft engines used gear, piston and centrifugal pumps.

Plunger pumps are widely used to supply fuel to the main combustion chamber as a pump for controlling the nozzle.

They allow you to adjust the flow rate independently of the speed change in the position of the swash plate. Such pumps have a relatively large mass (especially pumps for high flow rates), are complex and susceptible to fuel contamination, reducing their reliability and life, the cost increases, worsens maintainability.

Gear pumps are fairly simple, reliable. With the same dimensions with a plunger pump, they have in 1,5. 2 times more performance, which, however, is rigidly related to the speed of rotation. In order to regulate the flow rate, the bypass devices are installed at the pump outlet, and excess fuel is transferred from the pump outlet to its inlet. With increasing altitude, the bypass value becomes larger and can reach 75% of the maximum pump capacity. This leads to an increase in the temperature of the fuel, which reduces the life of the control equipment, worsens the use of fuel for cooling in the engine lubrication system. Such pumps are used to supply fuel to the main combustion chamber.

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